The present invention relates to a semiconductor device, and more particularly, to a technique which effectively allows application of a semiconductor chip (pellet) in different kinds of packages. It also relates to a technique effective for the formation of a resin-encapsulated semiconductor device employing a single in-line package structure.
Dual in-line type packages (DIP type packages) have heretofore been mainly used for RAMs up to a 256k-bit dynamic RAM. However, with higher integration, a package which permits a high density mounting has been desired. Consequently, particularly in dynamic RAMs of 1M bits or more, there is an increasing demand for packages other than DIP type packages, such as small out-line type (SOJ type) packages and zigzag in-line type (ZIP type packages).
Typically, a resin-encapsulated semiconductor device using a ZIP (zigzag in-line package) structure is a resin-encapsulated semiconductor device of high mounting density. In the resin-encapsulated semiconductor device, a semiconductor pellet mounted on the surface of a tab is tightly encapsulated with a resin. External terminals of the semiconductor pellet (i.e., the bonding pads) are connected electrically by way of bonding wires to the ends of inner leads on one side. The ends on the other sides of the inner leads are integrally constituted with outer leads. A plurality of these outer leads (external pins) are disposed along one surface of the resin-encapsulated portion in a zigzag form.
A resin-encapsulated semiconductor device using such a ZIP structure can be mounted on a mounting substrate by way of outer leads thereof. In the resin-encapsulated semiconductor device, the device-forming surfaces of the semiconductor pellet, inner leads and outer leads are respectively arranged substantially vertically to the mounting substrate. That is, the resin-encapsulated semiconductor device of the ZIP structure occupies a smaller area and has a higher mounting density on the mounting substrate as compared with DIP (dual in-line package), SOP (small out-line package) respectively.